web.xml中的load-on-startup是否可以用于在启动时加载任意类? [英] Can load-on-startup in web.xml be used to load an arbitrary class on startup?

问题描述

如何在Tomcat启动时加载任意类? 我看到了web.xml文件的load-on-startup标记，但是可以使用它吗，应该如何实现我的课程?

How can I load an arbitrary class on startup in Tomcat? I saw load-on-startup tag for web.xml file, but can I use it and how should I implement my class?

<servlet-name>??</servlet-name>
<servlet-class>??</servlet-class>
<load-on-startup>10</load-on-startup>

推荐答案

用于指定servlet的加载顺序.但是，当您听起来更想寻找与Webapp启动有关的信息时，servlet更适合控制，预处理和/或后处理HTTP请求/响应.在这种情况下，您宁愿使用ServletContextListener.

Those are meant to specify the loading order for servlets. However, servlets are more meant to control, preprocess and/or postprocess HTTP requests/responses while you sound like to be more looking for a hook on webapp's startup. In that case, you rather want a ServletContextListener.

@WebListener
public class Config implements ServletContextListener {
    public void contextInitialized(ServletContextEvent event) {
        // Do your thing during webapp's startup.
    }
    public void contextDestroyed(ServletContextEvent event) {
        // Do your thing during webapp's shutdown.
    }
}

如果您尚未使用Servlet 3.0(因此无法使用@WebListener)，则需要按如下所示在web.xml中手动注册它:

If you're not on Servlet 3.0 yet (and thus can't use @WebListener), then you need to manually register it in web.xml as follows:

<listener>
    <listener-class>com.example.Config</listener-class>
</listener>

另请参见:

• Servlet容器生命周期

See also:

• Servletcontainer lifecycle

这篇关于web.xml中的load-on-startup是否可以用于在启动时加载任意类?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！